Heptazine-based porous polymer for selective CO2 sorption and visible light photocatalytic oxidation of benzyl alcohol

By Xu, Congying; Qian, Li; Lin, Junyu; Guo, Zhiyong; Yan, Dan; Zhan, Hongbing
Published in Microporous and Mesoporous Materials 2019

Abstract

Heptazine units with highly rich nitrogen sites were employed to fabricate a new porous organic polymer (POP-HE) via direct coupling of 2,5,8-trichloro-s-heptazine and 4,4?,4?,4?-(ethene-1,1,2,2-tetrayl)tetraaniline with the mild base N, N?-diisopropylethylamine (DIPEA) in tetrahydrofuran (THF) solution. POP-HE displays good CO2 uptake capacity (50.6 cm3 g?1, 10 wt%, 1 bar/273 K) and highly selectively adsorptive separation of CO2 over CH4 under ambient conditions. Impressively, at 273 K, the predicted IAST selectivity of POP-HE is 47.0-13.4 for the natural gas mixture (CO2/CH4 = 5:95) at pressures varying from 0 to 1 atm. Meanwhile, the result of calculated band gap value based on Tauc plot motivated us to investigate its photocatalytic activity. POP-HE was applied as heterogeneous photocatalyst for visible light-induced selective oxidation of benzyl alcohol to benzaldehyde, and exhibited great conversion of 33.6% under irradiation of white LED light, which is much higher than that of g-C3N4. Moreover, POP-HE can be recycled up to three times without significant decrease in catalytic activity.

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